1. Field of the Invention
The present invention relates to an electrical connector, and more particularly to an electrical connector having a retention system for retaining the electrical connector on a printed circuit board.
2. Description of the Related Art
It is well known to provide an electrical connector mountable to a printed circuit board (hereinafter PCB), wherein the connector has terminals electrically engaging with respective electrical circuit traces on the PCB. Such a connector has a problem that the electrical connections between the terminals and the circuit traces of the PCB are often subjected to external stresses, which sometimes will cause the connections break. To resolve the problem, board locking mechanisms have been introduced in.
U.S. Pat. No. 5,249,983 (the '983 patent) and U.S. Pat. No. 5,228,873 (the '873 patent) each discloses a connector having bolt/nut devices for retaining the connector to a PCB, thereby securing the electrical connections between terminals of the connector and circuit traces of the PCB. Referring to FIGS. 1 to 3B of the '983 patent, the connector comprises a dielectric housing 1. The housing 1 defines a pair of nut-placing recesses 6 in a top wall thereof and a pair of bolt-inserting apertures 11 extending through a bottom wall thereof and communicating to respective recesses 6. A nut 13 is interferentially fitted in each recess 6. Once the connector is placed onto a PCB 17 with through holes 18 corresponding to the apertures 11, a bolt 20 is inserted in each through hole 18 and through respective aperture 11 along a bottom-to-top direction, and then screwed into the nut 13. It is noted that each nut-placing recess 6 is further formed with extended projections 10 on an internal surface thereof to interfere with the nut for retaining the nut therein.
However, when the nuts 13 are assembled into the recesses 6, additional tools have to be used. Furthermore, in order to secure the nuts 13 in the recesses 6, a close tolerance is required between the nuts and the projections 10 of the recesses. As a result, requirements for accuracy of the projections are tremendous high which inevitably increases the whole cost of the connector. For example, if the size of each projection of the recess is a little larger than a standard size, the nut could not be fitted in the recess, and if the size of each projection is a little smaller than the standard size, the nut could not be secured in the recess and would be pushed out as the bolt 20 intents to engage with the nut.
Taiwan patent issue No. 517885 having the same inventor and the same assignee with the invention, discloses a connector having a downward type retaining means for nuts. As is shown in FIGS. 2 and 4 of the 517885 patent, the connector comprises a housing 10. The housing 10 has a pair of mounting portions 12 at opposite ends thereof. Each mounting portion 12 includes a latch 16 formed in a top wall thereof and having a protrusion 160 projecting from a distal end of the latch, a mounting hole 123 extending therethrough, and a receiving cavity 121 corresponding to the latch 16 and communicating to the mounting hole 123. A nut 40 is assembled into the receiving cavity 121 from a side wall of the mounting portion 12 and engages with the protrusion 160 of the latch 16 to be prevented moving out of the cavity 121. When a bolt (not shown) is screwed into the nut 40, the nut abuts against the latch 16 and the housing 10. By this way, the nut can be assembled into the receiving cavity without additional tools being used, and a loose tolerance is allowable between the nut and the receiving cavity/the latch, thereby requirements for accuracy of the receiving cavity and the latch are relatively lower because there is no interference between the nut and the receiving space to prevent the nut moving upwardly.
Since the latch and the receiving cavity are formed on a top end of the housing, the bolt requires a long length to extend through the PCB and the housing to engage with the nut. Such board locking mechanism is not adapted for a high profile connector, because a longer bolt is required, which is impractical and neither manufacture nor cost efficient. In addition, if the housing has other structures at the top end thereof, such latch and receiving cavity for nuts will result in increasing the size of the connector, which is obviously undersirable for designers with the ever-increasing miniaturization of electronic circuit.
Hence, an improved electrical connector is required to overcome the disadvantages of the prior art.